[Treatment of residual acoustic neurinomas]

Generally the main objective of acoustic neurinoma (AN) surgery is to totally remove the tumor associated with minimum morbidity. Nevertheless, in some cases residual tumor fragments are intentionally or accidentally left in place. These residues can lead to new growth. The present study provides a retrospective analysis of 14 cases of residual AN have undergone surgery at the Otology Group in Piacenza from 1987 to 1999. All these patients had previously undergone at least one retrosigmoidal exeresis although only one had been performed at the Otology Group. All patients except 1 were affected by anacusia at the time of surgery. The list of post-operative deficits included 2 hemipareses, 3 irreversible facial paralysis with consequent corneal opacity in 2 cases, 1 dysmetria and 1 paralysis of the abducent nerve. The patients had also undergone the following additional treatments: 1 emergency revision to drain a cerebellar hematoma, 3 ventricle-peritoneal derivations, 1 double application of stereotactic radiotherapy and 2 surgical procedures for facial plasty. Ten cases underwent the revision surgery at the Otologic Group using a translabyrinthine approach and 4 using a transcochlear approach. Tumor removal was deemed complete in all cases. The sole post-operative complications were a subcutaneous hematoma at the point where abdominal fat was removed and a temporary paralysis of the abducent nerve. Post-operative hospitalization was an average of 6.9 days. Analysis of the results showed that AN must be operated at selected centers in order to reduce the post-operative neurological deficit and the percentage of residual tumor. It also indicated that the retrosigmoid approach has a higher risk of accidentally leaving tumor residues than the other approaches. Finally, in the presence of a residual AN, the translabyrinthine approach offers the greatest advantages.